Friday, December 16, 2011

Bone Health - Osteoporosis and Nutrients for Bones

Osteoporosis and bone health are in the news and pharmaceutical companies are hoping you are worried. A new class of drugs called biphosphonates (Fosamax, Boniva, etc.) have become the “go to” drugs for Allopathic Medicine physicians in treating older patients with decreased bone density (osteopenia or osteoporosis). But are these drugs safe? And if they are not, what can we actually do to keep our bones strong and healthy?Bones are very complex living systems. They are constantly being created and destroyed, in a process called bone remodeling, throughout our lives. Your bones are like a scaffolding upon which the rest of your body is built. Muscles, tendons, ligaments, and just about everything else is in some way anchored to your bones. They are what gives your body its human form, allows you to walk upright, protects vital organs like your brain, and basically prevents you from being a puddle of goo on the floor.Since bones are so strong, it might not seem like we need to do very much to protect them. After all, they are strong enough to literally carry us for our whole lives. But bones are a living system that need to be maintained, otherwise they can degrade to the point that they become brittle and break easily.

WHAT ARE BONES?When most people think of bones, they probably picture a skeleton that you might see in a science classroom or the cartoonish ones that are out at Halloween, but what are bones really like? Unlike either of these common images, bones in our body are very much alive, not just a hard anchor, independent from our bodies.The basic scaffolding upon which the bone minerals are deposited is a material called collagen. Into this matrix of collagen, the bone building cells deposit a chemical called hydroxyapatite, the main component of “bone mineral”. Because it naturally forms into hexagonal crystals (six sided crystals), this organization is very efficient (i.e. low weight and very strong). This hexagonal structure is found in nature in many places like honeycomb, where it provides both strength and a very high volume for storage. We will get to why this is so important later in this post.But bones are more than just a hard surface for your muscles and tissues to anchor onto, they also perform vital functions in your body. Inside your bones, bone marrow is responsible for creating new red blood cells. Bones also act as a storage place for minerals, fat (in the form of fatty acids), and some types of hormones (e.g. growth hormone).

BONE ENGINEERING: OSTEOBLASTS AND OSTEOCLASTSBones are engineered just like bridges need to be engineered. Healthy bone use osteoblasts and osteoclasts to remodel bone in very sophisticated ways. Healthy bone must be light (or we could not move) and yet strong. This is not easy. The balance of osteoblasts (bone forming cells) working with osteoclasts (bone destroying cells) allows the body to form amazingly complex structures within our bones that just happen to be strongest where we need it most and yet light in weight everywhere possible.Osteoblasts are the cells that are responsible for growing bones and maintaining bone health. The name comes from Greek words and literally translates to “Bone Germ” (in this sense, germ means seeder). The osteoblast cells take all the minerals that make up bone, and deposit them into the collagen structures that make up the scaffolding of our bones. If you break a bone, it is the osteoblasts that are responsible for knitting the bones back together. They also are the cells that cause bones to grow during adolescence and puberty. After puberty, these cells start to decrease in number and continue to do so through adulthood.When your bones undergo stress (e.g. heavy exercise or slight injury), osteoblasts in the area get a signal that they need to work on strengthening the most stressed areas of the bone, making those areas thicker, denser, or otherwise stronger. It is this natural signal that translates physical shocks to making stronger bones in places were it most makes sense for the overall structural integrity of the bone and the rest of the skeleton. We don’t all walk or move exactly the same way through our entire lives, so it makes sense that the body should have some way of adjusting to the changing demands we put upon it. Osteoclasts, on the other hand, are responsible for breaking down bone minerals. Osteoclast, again from Greek roots, translates from words for “bone” and “broken”. Osteoclast cells move into areas of the bone and pull out the minerals from the collagen scaffolding. This is important, especially if your body is low in calcium for some reason, as it can pull what it needs from your bones so you don’t die (you need calcium for a number of things, like keeping your heart beating). However, when too much calcium (or any other mineral) is removed from your bones, they can become structurally weak and prone to breaking (what we call osteopenia and osteoporosis).While this may seem like a bad idea, the osteoclast cells are an important part of the way your body optimizes your bones. Osteoblast cells are responsible for strengthening areas of your bones that undergo stress, but that stress isn’t always in the same places. Without osteoclasts to balance this growth out, you would wind up with extremely dense bones that are very heavy and not very flexible. Moreover, bones that are dense in the wrong places can cause stress on less strong areas, possibly making breaks more likely.

THE BONE WEAVERSThe other key part of the osteoclast and osteoblast balance is related to injuries. When you injure a bone, osteoblasts immediately try to knit the small (or large) cracks so that you can get back into action as soon as possible. But the way that they do these “quick fix” repairs is not necessarily as strong as the way they grow bones normally, when they can take their time. Osteoblasts normally produce bones in what is called a lamellar pattern, where the collagen is laid down in sheets. This pattern adds a lot of strength to the bones. The emergency repair mode, however, just lays down the bone as quickly as possible and in no particular pattern. While this is good for quickly repairing bones the short term, it is hardly elegant or efficient. So, when your body gets a chance to start repairing damage properly, the osteoclasts clear out the disorganized bone cells slowly, allowing the osteoblasts to lay the sheet pattern again.BONE DENSITYThe “standard” measure of bone health in allopathic medicine is a test called a “bone density scan”. This test allows doctors to see (using 2 types of x-rays) how dense your bones are in a few key places in the body. Though the test can be helpful in some cases, it also has a number of flaws.First of all, the bone density test is only really useful if you have previously done a “baseline” test that shows what your bone density looks like under normal conditions. Since most people don’t have a bone density test done until they first suspect that bones might already be weakened, this doesn’t typically give a good comparison point. Every person has a different natural bone density based on a huge number of variables from genetic predisposition to how much exercise they do and what their diet is like. Without a good picture of your “healthy” bone density levels to compare other scans to, it’s more or less a guessing game.The second problem with bone density tests is that they do not show you anything about the structural integrity (or engineering quality) of your bones. Bone density tests show how much of certain minerals exist in your bones (they show up whiter when more hydroxyapatite exists and less white when less is present). But as we have seen, simply knowing the amount of minerals in a bone does not tell you if it is laid down in a healthy manner.OSTEOPOROSISWhen bone density reaches a low enough level that there is a serious risk of fractures, the condition is called osteoporosis. Osteoporosis, again from Greek roots, basically translates as “porous bones” which is pretty descriptive of the condition. Osteoclasts pull minerals out of the bones, leaving them porous and brittle, and the osteoblasts can’t put the minerals back in. Once the bones reach this fragile state, they are at increased risk for fractures, the most common of which happen in the vertebral column (spine), rib, hip, and wrist.There are two types of osteoporosis, type 1 and type 2. Type 1 occurs in women and usually after the onset of menopause. This is because estrogen plays a key role in the formation and resorption of bone. The specific decline in estrogen production following menopause both increases the rate of bone resorption by osteoclasts as well as decreasing the ability of osteoblasts to build new bone that normally takes place in weight-bearing bones. Type 2, or senile osteoporosis, occurs in many people past the age of 75, but at a rate of 2 to 1 for women and men, respectively.The people most at risk for developing osteoporosis are women, especially those who are smaller or underweight. Taking supplements can help to delay or even prevent osteoporosis, especially when combined with exercise.You may also have heard of a condition called “osteopenia”. This is a term meaning that bone density is “less than normal but more than osteoporosis”. While this clinical definition is useful in monitoring patients who could be at risk of a decreasing bone density, there is some controversy over its use for marketing by drug companies. The fact is that there is a large group of people who might have osteopenia, but will never develop osteoporosis.Unfortunately, the definition of osteopenia is so loose and the drug companies are pushing their potentially dangerous drugs, like biphosphonates, onto the public for treating osteopenia. If your doctor suspects that your bone density is low enough that you fall into the category of having osteopenia, discuss all your options and whether treatment of any kind is warranted or if you should wait to see if it improves with supplementation of minerals. Taking prescription medications for osteopenia may not be the best course of action, especially if you have only recently been diagnosed.BONE REMINERALIZATIONAs we age, the number of osteoblast cells we have goes down, as does the remaining osteoblast cell activity. This is normal because when we stop growing after puberty, we don’t generally need the same number of bone growing cells. However, this can lead to problems if you don’t provide our body with sufficient minerals to replace what your body uses on a regular basis. If you have low levels of these minerals you need, your body will signal osteoclasts to pull those minerals out of your bones, where they are stored. Making sure you are getting enough of these minerals from diet or supplements is essential for maintaining bone health, especially as you get older.While the main bone mineral (hydroxyapatite) is primarily made up of calcium and phosphorus, several other nutrients, including magnesium, potassium, vitamin C, vitamin K, several B vitamins, and carotenoids (converted to vitamin A by your body), have been shown to be more important than previously realized. Osteoblasts, in order to produce the matrix and deposit bone minerals there, need the minerals found in bones, namely calcium, magnesium, and phosphorus. Additionally, osteoblasts require zinc, copper, and sodium, in order to process and assemble bone minerals. It is important to get all of these minerals and nutrients in proper proportion so that they can best support bone growth and repair. If certain ones are lacking (e.g. vitamin D, calcium, magnesium), then it won’t matter how many of the others you have.

A well engineered bridge resembles
the structure of healthy bone.

Eating and taking supplements for the minerals needed for bone growth or repair is not enough; you also have to make sure they actually get absorbed by your body. One of the best ways to enhance absorption of these minerals is by eating enough fiber. Fiber has been shown to increase absorption of a wide number of key nutrients in the small intestine.Certain forms of the individual supplements are more easily absorbed than others. Of particular note in this category is Calcium. Most calcium supplements are the inexpensive calcium carbonate. However, calcium carbonate requires high acidity in order to be broken down enough to absorb properly. This can be a problem for older people (who don’t produce as much stomach acid) or for people taking antacids or acid blocking medications (e.g. H2 blockers or Proton Pump Inhibitors). Calcium citrate, while more expensive, is more easily absorbed by your body and may be a better choice for some people.This illustrates the need for a quality source of vitamins and minerals, produced in the right quantities, and composed of quality ingredients. In a previous post, we discuss the qualities of a good supplement and good supplement manufacturers. As always, check with your health care practitioner to get the right mix of vitamins and minerals for your body and your health.SUPPLEMENTS

Magnesium - While the exact mechanism of magnesium in bone health is not entirely clear, it is well known that magnesium is needed to help absorb calcium. About 60% of all the magnesium in your body at any time is stored in bones, with less than 1% in the bloodstream (though this level is very closely regulated). It has also been demonstrated that insufficient levels of magnesium can lead to osteoporosis by promoting bone resorption and reducing bone growth. Clearly the importance of magnesium in bone health is important, even if it is not completely understood.

Zinc, Copper, and Sodium - These three are needed by osteoblasts for forming and depositing bone mineral (hydroxyapatite) into the collagen matrix of the bones. While a balanced diet typically provides enough of these, a good quality multivitamin can also provide more than enough to make up for a minor deficiency.

PRESCRIPTION MEDICATIONSThe main prescription medications for treating a loss of bone density (usually in post-menopausal women) are a class of drugs called biphosphonates. This class of drugs is marketed under many different names like Actonel, Actonel+Ca, Aredia, Boniva, Didronel, Fosamax, Fosamax+D, Reclast, Skelid, and Zometa. Many of these drugs were approved for use based on studies that paired them with supplements of calcium and vitamin D, making their overall effectiveness versus placebo (with no vitamin D or calcium) questionable; vitamin D and calcium are already known to be effective in treating low bone density without the medications, so how much effect are the medications really having?Even assuming these drugs are effective, they are essentially increasing bone density by cheating; they simply slow down osteoclasts, preventing bone resorption, but don’t actually increase bone growth by osteoblasts where you need it. Obviously this would help increase overall bone density, but it doesn’t necessarily make it so your bones are (properly) more dense in places they need to be. In most cases, the body might be removing bone mineral in some places in an attempt to better optimize the overall structure and strength of the bone.In addition to these concerns, recent studies show some side effects that are alarming. Long term use of biphosphonate drugs has been linked to a very serious (and normally very rare) fracture of the femur (thigh bone). Even more alarming is that over 25% of people who had this complication (if you can call a broken leg simply a complication) from the medications also developed a fracture in the other leg too. Two broken thigh bones doesn’t exactly make for a ringing endorsement of a drug that is supposed to strengthen bones by increasing bone density. Clearly bone density is not the end-all of preventing broken bones.EXERCISE IS STILL THE BEST MEDICINEBecause osteoblasts rely on signals from stressed bones, exercise is one of the best ways to stimulate bone growth. On top of that, strengthening the muscles around your bones, especially muscles in the core of your body, can help reduce the risk of falling and the sudden shock and forces on bones if you happen to accidentally fall, making fractures less likely.If your bones are at risk of breaking due to low bone density, there are still low impact exercises you can do to strengthen muscles and stimulate bone growth. While shock and impact forces do stimulate osteoblasts, doing simple, low impact exercises while adding or carrying weights can do so at least as effectively without the added risk from impacts. Even simple exercises like walking, where you deliberately increase the amount of weights you carry, and therefore support with your bones, are shown to be of significant benefit.CONCLUSIONIn the end, it may be that aiding osteoblast activity through nutrition and supplements means that the flexibility of your body’s natural system of optimizing bone strength can remain intact. It isn’t always as simple as “more bone density is better”. The structure and balance of bone density in key places may be more important, which is why we evolved this dynamic system in the first place. There are still reasons that bone density can be helpful in determining risk, but the issue of bone health appears to be more complex.It is still important to discuss the nutritional and prescription medication options with your health care practitioner, as every person’s body is different. For some people, the medication option may be a good idea, at least in the short term. Make sure that your concerns are considered carefully by your health care practitioner before committing you to a course of action. Discuss all the options and make an informed choice as to which is best for you.

-----

Researched and written by Dr. Rebecca Malamed, M.D. with assistance from Mr. Malcolm Potter.